Control for two-temperature refrigerators



Patented Oct. 25, 1938 UNITED STATES.

PATENT orruzs CONTROL FOR TWO-TEMPERATURE REFRIGERATORS Leslie B. M.Buchanan, Springfield, Mass assignor to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application October 22, 1936, Serial No. 106,976

' 14 Claims.

posed in the high and low temperature chambers to maintain the chambersat different refrigerated temperatures. It has been suggested,heretofore, to control the cooling effect of the higher temperatureevaporator by operating a fan in the warmer compartment for circulatingair over the warmer evaporator in response to 15 the temperature of thewarmer compartment or evaporator. In accordance with my invention, sucha system is utilized, and in addition preference is given to the coldercompartment so that it will receive refrigeration when required, re-

gardless of the heat load on the warmer evaporator.

In the aforementioned prior art devices, the

fan was usually stopped with the condensing unit,.

or only was operated when the temperature of the warm compartment roseabove a predetermined minimum. Such a system has several disadvantages.For example, the air in the warm compartment circulates very slowly whenthe fan is inactive with the result that some portions of the warmercompartment rise to an unsafe temperature. Furthermore, in certain typesof two temperature systems, the warmer evaporator may operate belowfreezing and collect frost, thusreducing its effectiveness and alsolowering the relative humidity in the warmer compartment in which it isdesirable to maintain a fairly high relative humidity. Furthermore, acertain amount of the thermal storage capacity of the warmer evaporatormay be lost.

- In accordance with my invention, therefore, in

normal operation preferably when the colderevaporator does not requirerefrigeration, I have devised various schemes for operating the fanafter the condensing unit "has shut down, preferably independently ofthe air temperature in the warmer compartment. For example, the fan maybe operated after the condensing unit shuts down until a predeterminedhigh temperature of the 50 warmer evaporator is reached, or means may beemployed for periodically stirring the air in the warmer compartmentafter the condensing unit has been shut down or the fan may runcontinuously regardless of the temperature of the 55 warmer compartmentor warmer evaporator until the, colder evaporator or compartmentrequires refrigeration.

Accordingly, itis a further object of my invention to effect forcedcirculation of air within the cooling chamber ofa refrigerator duringperiods when the chamber is refrigerated.

A further object of my invention is to render the air translating meansin one cooling chamber of a two chamber refrigerator inactiveduringperiods when the other chamber calls for cool- 10 mg.

A still further object of 'my invention is to effect circulation of airin thecooling chamber of a refrigerator for a period of time subsequentto terminating refrigeration of the evaporator 15 therein.

Another object of the invention is to periodically eifect circulation ofair in the coolingchamber of a refrigerator.

These and'other objects are efiected by my 20 invention as will beapparent-from the following description and claims taken in connectionwith the accompanying drawing, forming a part of this application, inwhich: j

Fig. 1 is a diagrammatic View of a refrigerat- 25 ing system arranged inaccordance with my invention; and,

Figs. 2 and 3 are diagrammatic views showing second and thirdembodiments of the. invention, respectively. 30

First embodiment (Fig. 1)

Reference will now be had to Fig. 1 in which I have shown a portion of arefrigerator cabinet III that includes relatively low and high tem- 35perature cooling compartments H- and [2, respectively; Evaporatorelements l3 and I4 abstract heat from the compartments .II and l2 andreceive refrigerant from a common condensing unit shown at IS. Thecondensing unit I5 40 includes a compressor l6 driven by a motor IT. Thecondensing unit l5 also includes a condenser l8 cooled in any suitablemanner, such as,'for example, by a motor driven fan I9.

Condensed refrigerant is conveyed from the condenser l8'to theevaporators l3 and by a conduit 2! in which a conventional high sidefloat valve 22 may be connected. The charge of refrigerant in the systemis such that liquid refrigerant substantially fills both evaporators l3and-l4. The system operates on the compressorcondenser-expander cycle inwhich the compressor unit l6 withdraws vaporized refrigerant from theevaporators l3 and I4 through a conduit 23 fand compresses it to arelatively high pressure prior to its delivery to the condenser l8. Thehigh pressure gas is cooled'and condensed in the condenser l8 and thenpassesto the float valve 22. The pressure of the liquid refrigerant isreduced as it passes through the float valve 22 to the evaporators I3and I4, wherein it is vaporized at low pressure forabstracting heat fromthe evaporators.- This cycle continues repeatedly during the period thatthe compressor l6 operates. e

The evaporator |3 may be employed forfreezing fluids contained in trays24 and for cooling the air' in chamber II to a relatively lowtemperature. The evaporator |4 cools the air in the chamber l2 in whicharticles of food or other perishables may be stored. Suitable means suchas, for example, a fan 25 driven by a motor 26 isemployed for providingforced circulation of air in the chamber |2, whereby a relatively highrate of heat transfer between the air therein and the evaporator I4 iseffected. During periods when the fan 25 is inactive, the rate of heattransfer is low so that refrigeration of the body of'air in the chamber2 is not effected to any material degree. Some limited cooling of theair is effected in the chamber |2- during inactive periods of the fan 25due to thermally induced air currents but it is relatively small. Ac-

cordingly, effective refrigeration of the air in the compartment |2accompanies operation of the fan 25 and, during inactive periods of thelatter, effective refrigeration ceases. The evaporators |3 and H arecooled by refrigerant vaporized in each at a substantially equalpressure at any one time and cool the media in their respectivecompartments to different temperatures due to the difference in the rateof heat transfer be-- tween the respective evaporators and the mediacooled thereby.

The temperature prevailing in the chamber II is controlled by athermostat 21, shown by way of example, of the gas type and including abellows 28 connected by a tube 29 to its temperature responsive bulb 3|.As is well understood, the bulb of a gas type thermostat contains asuitable volatile fluid, the pressure of which is a function of itstemperature. Accordingly, the bellows 28 expands and contracts as thetemperature of the bulb 3| increases and decreases. Preferably, the bulb3| responds directly to the temperature of the evaporator l3, beingsecured thereto as shown but it will be understood that it may bedisposed otherwise in the chamber II. A lever 32, pivoted at 33, isactuated by the bellows 28 and carries movable contacts 34 and 35 of apair of switches '36 and 31, respectively,

which switches include stationary contacts 38 and 39.

The temperature of the air in the chamber I2 is controlled by a bimetalthermostat 4|, but which may be of any suitable type. It includes anexpansible bimetallic member 42 that carries a movable contact 43, thelatter being engageable with a stationary contact 44 for defining aswitch structure 45. The controlling operation of the thermostats 21 and4| will be referred to hereinafter.

The source of power for the various elements of my improved apparatus isrepresented by line conductors L1 and L2. The compressor motor I1 isconnected directly to conductor L2 and to the conductor Li'by means of aconductor 46 controlled by the switch 36 of the thermostat 21.Accordingly, when the temperature of the evaporator l3 rises to apredetermined value, the motor I1 is energized by the foregoing circuitand One termi-' the switch 31 of thermostat 21, and having a thermallyactuated device 49 connected therein.

The construction of the device 49 will now be described.

Included in the elements of the device 49 is a heat responsive member ordisk 5|, preferably of bimetal construction and defining the bridgingmember of a switch structure 52 having stationary contacts 53. The disk5| is so constructed that it snaps into engagement with the contacts 53when its temperature attains a predetermined high value and snaps to acircuit opening position out of engagement with the contacts 53 when itstemperature is reduced to a predetermined value. The device 48 may bedisposed in any suitable location, preferably, ex-

terior of the cooling compartments II or 2. A

relatively high resistance 54 is bridged across the contacts 53 andis'shunted during periods when the disk 5| bridges the contacts 53,whereby the resistance 54 is deenergized. In the open position of theswitch 52, the resistance 54 is energized for heating the disk 5|.

Accordingly, when the switch 31 of thermostat 21 is closed, theresistance may be energized by a circuit'including conductor L1, closedswitch 31, conductor 48, resistance 54, fan motor 25, and

conductor L2. The heated disk 5| snaps to a circuit closing positionafter a predetermined period of time andenergizes the fan motor 26. Airis then circulated in the high temperature chamber |2. As the heater 54is shunted by the disk 5|, it cools and, after a predetermined period oftime, the disk snaps to its open position and the fan 25 and motor 26stop. The resistance 54 is then heated and this periodic cycling of thefan motor 28 continues as long as switch 31 is closed.

A second resistance 55 of relatively low value is disposed in heattransfer relation with the disk 5| and is connected in the conductor 41,

controlled by the higher temperature thermostat 4|. When the compressormotor I1 is energized by the thermostat 4|, including conductor 41, theresistance is connected in series with themotor l1 and, therefore, heatsthe disk 5| sufllciently to close the switch 52 and continuouslyenergize the fan motor,26. Therefore, during periods when the hightemperature thermostat 4| calls for cooling, the fan 25 is operated tocontinuously effect forced circulation in the chamber 2. Circulation ofair in the chamber l2 for a period of time subsequent to the opening ofthermostat 4| is effected, due to the heat stored in the disk 5| by theresistance 55.

The device 49, therefore, functions to effect forced circulation in thechamber l2 during periods when its thermostat 4| calls for cooling andto periodically effect air circulation during periods when boththermostats 4| and 21 are satisfied. During periods when the thermostat21 calls for cooling,'the fan motor 26 is deenergized,

as the switch 31 is open.

Operation of Fig. 1 I The position of the apparatus shown in Fig. 1

indicates that the temperatures prevailing in the are satisfied. In thisposition, the fan 25 is periodically operated by the motor 26 to effectcirculation of air inthe chamber I2, due to the closure of switch 31 andthe aforementioned cycling of the device 49. This operation keeps theair stirred in the chamber l2 whereby more even temperatures prevailthroughout.

Due 'to heat load in the chambers II and I2, the pressure andtemperature of both evaporators l3 and 4 rise. As the temperature of theevaporators rises to a predetermined value, the thermostat 21 operatesto call for cooling, whereby the switches 36 and 31 close and open,respectively. The former eflects operation of the condensing unit |5 asthemotor I1 is energized as described heretofore. The fan 25 is renderedinactive to'efiect circulation of air in the compartment |2 due to theopening of switch 31.

The condensing unit l5 operates to translate refrigerant to theevaporators' l3 and M for vaporization therein. Refrigeration of thechamber II is effected and, while the temperature of the evaporator I4is depressed to a low value, refrigeration of the air in chamber I2 isnot effected to any material degree due to the inactivity of'the fan 25and the resultant poor rate of heat transfer between the air and theevaporator I4. As the temperature of the evapcrators I3 and |4 isdepressedto the value at which the thermostat 21 is satisfied, theswitch 36 is opened and the switch 31 is closed. Opening of switch 36terminates operation of the condensing unit l5 and closing of the switch31 conditions the circuit for operation of the fan motor 26.

Assume the temperature of the air in compartment 2 rises, to the valueat which the thermostat 4| calls for cooling, and that the thermostat 21is satisfied. The switch 45 closes and energizes the compressor motorwinding |1 through the circuit including conductor 41 and resistor 55.Circulation of refrigerant is initiated and continuous operation of thefan 25 is effected due to the heating of disk 5| by resistor 55,previously described. A high rate of heat transfer between the air incompartment l2 and the evaporator I4 is effected and cooling of the airincompartment I2 is obtained. At this time, the majority of refrigerantcirculated is vaporized in the evaporator l4 due to the high heat loadthereon.

During periods when both chambers II and |2 require cooling, the colderchamber v|| takes preference over the warmer chamber |2 as the switch 31of the thermostat 21 is open for rendering the motor 26 and the fan 25.inactive. Refrigeration of chamber II is, therefore, effected inpreference to chamber I2. After the chamber II is satisfied, control ofthe fan 25 and the condensing unit is assumed by the thermostat 4|, asis well understood.

Second embodiment (Fig. 2) In the showing of the second embodiment of myinvention (Fig. 2), I have, for the sake of though the motor |1 of thelatter is shown. Elements shown which are common to both embodiments areindicated by the same numerals.

In the present embodiment, I show a thermostat 6| of the gas type havingits bulb 62 disposed in heat transfer relation with the air in thechamber 2. The thermostat 6| actuates a movable contact 63 intoengagement with stationary contacts 64 and 65 in response to apredetermined high temperature of the air-in the compartment l2 anddisengages the same in response to a predetermined lowtemperature oi theair. The contacts 63, 64 and 65 define a switch structure 66. Themovable contact 63 is connected to the line L1 and the contact 64 isconnected to a conductor 61 extending to one terminal of the fan motor26. and controlled by the switch 31 of the thermostat 21. The contact 65of the thermostat 6| is connected to a conductor 68 extending to oneside of the winding l1 of the compressor motor and may include aninductive reaetance 69, the purpose of which will be referred tohereinafter. The other ter-' minals of the fan motor 26 and compressormotor H are connected to the line L2, as shown.

A condensing unit (not shown) similar to that shown in Fig. 1 iscontrolled by the switch 36 of the thermostat 21 which switch isconnected in ,a conductor 1| extending from line L1 to the motor windingI1. A resistor 12 disposed in heat transfer relation with athermo-responsive disc 13 is connected in the conductor 1| and is heatedincidental to the energization of the motor winding H by the switch 36.The disc 13 is disposed in heat transfer relation with the evaporator l4and operates to bridge stationary cuit extending from line L1 to the fanmoter 26.

When the evaporator I4 is below a predetermined temperature, forexample, 35 F., the contacts 14 are bridged by the disc 13 and the fanmotor 26 operates to circulate air within the chamber I2. The fan motor26 may be deenergized by the disc 13 when it is actuated to opencontacts 14 in response to an evaporator temperature above 35 F. Thedisc 13maybe actuated in an opening direction independently of thetemperature of the evaporator l4 by means of the resistor 12 whenenergized.

Operation of Fig. 2

The position of the apparatus, as shown,'indimand cooling. Boththermostats 21 and 6| are satisfied and, therefore, their respectiveswitches 36 and 66 are open. The condensing unit is idle at this time.In this position, the fan may or may notbe operating, dependent uponwhether temperature of the evaporator I4 is above or below 35 F. If itis below this value, the disc 13 bridges the contacts 14 and the fan 251s operated by its motor 26; the latter being energized by a circuitincluding line L1, conductor 15, mo-

tor 26 and line 1c. Accordingly, any ice formed I on the evaporator I4is melted and the air in the, chamber I2 is circulated and cooled.

Assumethe chamber H and evaporator |3 require cooling. The thermostat 21operates to close switch 36 and to open switch '31. Opening of thelatter is of no importance for the moment as switch 66 is open. Closureof switch 36,'however, energizes the conductor 1|, heater 12 and thecompressor motor winding I'I. Circulation of refrigerant by thecondensing unit is initiated and the fan 25 is rendered inactive due tothe opening of the contacts 14 by the heated disc 13. Refrigeration ofthe chamber II is effected as described heretofore in connection withFig. 1.

As the temperature of the evaporator I3 is depressed to the desiredvalue, the thermostat 21 moves to its satisfied position, whereby thecondensing unit is stopped and the heater l2 deenergized. As thetemperature of the evaporator H is relatively low, the disc closes thecontacts H and the fan '25 operates to circulate air for melting anyaccumulated frost on the evaporator l4.

Assume that the temperature of the air in the chamber l2 rises to thepredetermined value at which the thermostat 6| moves to its switchclosed position and that the thermostat 21 is satisfied. The condensingunit is operated as its motor winding I1 is energized by a circuitincluding the line conductor L1, movable contact 63, contact 65,reactance 69, conductor 68, winding I1 and line conductor L2. The fanmotor 26 is energized by a circuit including line conductor L1, contacts63 and 64, conductor 61, closed switch 31 of the thermostat 21, fanmotor 26, and line conductor L2. The air in the chamber -I2 is,therefore, circulated and cooled as described, heretofore. As thetemperature of the air in the chamber I2 is depressed to the desiredvalue, the thermostat 6! is actuated to the position shown, wherebyoperation of the condensing unit is terminated. The fan 25 continuesoperation, however, as its motor 26 continues to be energized due to thebridging of the contact H by the cold disc 13. 'Ihefan 25 stopsoperating when the temperature of the evaporator l4 and disc 13 rise tothe assumed value of 35 F.

In the event of a demand for cooling from both compartments, thecondensing unit will be operated by the preferred thermostat 21 in themanner described heretofore so that refrigeration of the coldcompartment II is effected and the fan 25 is inactive. At this time, themotor winding I1 is connected to the line con-.- ductor L1 throughparallel circuits, one of which includes the heater or resistance 12 andthe other of which includes the reactance 69. Accordingly, current flowsin the conductor H and resistor 12 due to the voltage drop across .thereactance 69, so that the fan 25 is rendered inactive by the heated disc13 as described. When the thermostat.2'| becomes satisfied, control ofthe condensing unit l5 and fan 25 is assumed by the thermostat 6L.

Third embodiment (Fig; 3)

In the third embodiment of my invention as shown in Fig. 3, certainparts shown in Fig. 1 are removed for the sake of clearness and elementsappearingin the present embodiment which tive when the latter calls forcooling of the chamber I l and is active at all other times. 7 Oneterminal of the motor 26 is connected to the line conductor. L1 and theother to a conductor 11 leading to the line 'conductor L2 and controlledby the switch 31.

The winding of the compressor motor II has one terminal connected toline conductor L2 directly and the other to a conductor 18. The

l2, to its circuit closed posito circulate air in the chamber I2 and toremove frost from the evaporator l4. As the thermostat 21 calls forcooling; the fan is rendered inactive by the opening of the switch 31and the winding oi the. compressormotor I1 is energized by the closureof switch 36. Accordingly, refrigerant is circulated for vaporization.in the evaporators l3 and I by the condensing unit. When the temperatureof the evaporator I3 is depressed to the desired value, thethermostat..21 is actuated to the position shown so that circulation ofrefrigerant is terminated and circulation of air in the chamber l2initiated.

When the thermostat I9 calls for cooling, the condensing unit is startedand, as the fan is operating, -refrigeration of the circulating air inthe chamber I2 is effected. As described heretofore, the rate of heattransfer is high at this time so that the major portion of thecirculated refrigerant is vaporized inthe evaporator I4. The refrigerantcondensing unit is stopped when the thermostat 19 becomes satisfied butcirculation of air in the chamber I2 is continued. During demands forcooling from both thermostats 21 and 19, the former controls, as the fan25 is stopped by the open switch 31 at this time.

From the foregoing, it will be apparent that T have provided improvedrefrigerating apparatus having separately refrigerated compartments,wherein the compartments are selectively refrigerated, with provisionsfor refrigerating one compartment in preference to' the other.Furthermore, my improved apparatus provides for forced circulation ofair in a chamber during refrigeration thereof and for a period of timesubsequent thereto. The invention provides for circulation of air incycles during inactive periods of the refrigerant circulating means andfor controlling circulation of air in accordance with the temperature ofthe evaporator cooling the air.

I have shown my improved apparatus having the low temperature elementrefrigeratedin preference to the higher temperature element, when bothrequire cooling, but it is to be understood that the higher temperatureelement may be given preference without departing from the spirit of myinvention. Refrigerating machinesv other than the compression type shownmay be departing from the spirit thereof, and I desire; therefore, thatonly such limitations shall be placed thereupon as are imposed by theprior art or as are specifically set forth in the appended claims.

What I claim is:

1. In refrigerating apparatus, the combination of means defining firstand second cooling chambers, an evaporator element associated with eachof thechambers, mea'nsfor circulating refrigerant through th'evaporatorelements,.means responsive to the temperature in one of the chambers forcontrolling the refrigerant circulating means, means for translating airin heat transfer relation with the evaporator element in the otherchamber, and means responsive to the operation of said temperatureresponsive, means and operative'for rendering said air translating meansineffective during periods when the temperature responsive means'callsfor cooling.

2. In refrigerating apparatus, the combination of means defining firstand second cooling chambers, an evaporator element associated with eachof the chambers, means for circulating refrigerant through theevaporator elements, first and second means responsive to temperaturespre vailing in the first and second chambers, respectively, forcontrolling the operationof the refrigerant circulating means, a fan fortranslating air in heat exchange relation with the evaporator element inone of the chambers, and means responsiveto the operation of thetemperature responsive means associated with the other of said chambersfor rendering the fan inactive during periods whenthe'temperatureresponsive means associated with the other chamber iscalling for operation ofthe refrigerant circulating means.

3. In refrigerating apparatus, the combina- I tion of means definingfirst and second cooling chambers, an evaporator associated with each ofthe chambers, means for circulating refrig-' erant through theevaporators, means responsive to predetermined high and low temperaturesobtaining within the first chamber for starting and stopping therefrigerant circulating means, a fan for translating air within thesecond chamber in heat transfer relation with the evaporator tlierein,means responsive to predetermined high and low temperatures obtainingwithin the second chamber for respectively initiating and terminatingoperation of the refrigerant circulating means, means for effectingoperation of the fan during periods when said second chamber re-- quirescooling and said first chamber is satisfied, and means responsive to theoperation of the temperature responsive means associated with the firstchamber for rendering said fan. inactive during periods when said firstchamber requires cooling. I

4. In refrigerating apparatus, the combination of a cabinet having acooling compartment therein, an evaporator for cooling the air in thecompartment, means for translating air within the compartment in heattransfer relation with the evaporator, means for circulating refrigerantthrough the evaporator, means responsive to a translating means forpredetermined periods of time during periods when the refrigerantcirresponsive to predetermined high and low tem-' peratures prevailingin the first chamber for initiating and terminating operation of therefrigerant circulating means, means responsive to a predetermined hightemperature prevailing in the second chamber for initiating operation ofthe refrigerant circulating means and said fan, said last-mentionedmeans being effective in response to a predetermined low temperatureobtaining in the second chamber for terminating operationof therefrigerant circulating means, and means for terminating operation ofthe fan subsequent to termination of operation of the refrigerantcirculating means by said secondmentioned temperature responsive means.

6. The combination as claimed in claim 5 having means operative duringperiods when the first-mentioned temperature responsive means calls foroperation of therefrigerant circulating means, for rendering the faninactive irrespective of demands for its operation by thesecond-mentioned temperature-responsive means.

'7. In refrigerating apparatus, the combination of means definingrelatively high and low temperature cooling chambers, an evaporatorelement arranged within each chamber, a refrigerant compressor forsupplying condensed re- .frigerant to the evaporator elements-forvaporization therein, first and second thermostats responsive totemperatures prevailing in the low and high temperature chambers,respectively,

said thermostats being effective in response toconditioning the fan foroperation during periods when the thermostat is satisfied andforrendering the fan incapable of operation when the thermostat is callingfor cooling, means for operating the fan during periods when the secondthermostat calls for cooling and when the fan is conditioned foroperation, and means forperiodically operating the fan duringperiodswhen both of saidthermostatsare satisfied.

' 8. In a refrigerating system having first and second chambers to berefrigerated, first and second evaporators for cooling the air in said[v chambers, respectively, means for circulating refrigerant through theevaporators, a fan for translating the air within the second chamber inheat transferring relation with its associated evaporator, meansresponsive to a predetermined temperature in the secondchamber forinitiating operation of the refrigerant circulating means, meanseffective when the temperature of the evaporator in the second chamberis below a predetermined value for effecting operationof the fan, meansresponsive to a predeterminedtemperature in the first chamber forinitiating operation of the refrigerant circulating means, and means-forrendering the fan inactive during periods when the temperatureresponsive means in the first chamber is calling for cooling.

9.-In a refrigeratingqsystem, the combination of means defining achamber to be cooled, an evaporatordispo's'ed for'cooling the air in thechamber, means for circulating refrigerant through the evaporator, a fanfor translating air within the chamber in heat transfer relation withsaid evaporator, means responsive to a predetermined high temperaturewithin the chamber for initiating operation of the refrigerantcirculating means and the fan, said temperature responsivechamber, meansfor circulating refrigerant through the evaporator, a fan fortranslating air within the chamber in heat transfer relation with saidevaporator, means responsive to predetermined high and low temperatureswithin the chamber for respectively initiating and terminating operationof the refrigerant circulating means, and means responsive to apredetermined high and low temperature of the evaporator forrespectively terminating and initiating operation of the fan.

11. In refrigerating apparatus, the combination of means defining firstand second chambers, an evaporator structure having first and secondportions disposed for cooling the air in the first and second chambers,respectively, means for circulating refrigerant through the evaporator,a fan for circulating air within one of the chambers in heat transferrelation with its associated evaporator portion, means responsive topredetermined high' and low temperatures of the evaporator portion inthe other chamber for starting and stopping operation of the refrigerantcirculating means, means for rendering said fan inactive during periodswhen said temperature responsive means effects operation of therefrigerant circulating means and for conditioning the fan for operationduring periods when operation of the refrigerant circulating means isstopped, and means responsive to the temperature of the secondevaporator portion for controlling the operation of the fan duringperiods when it is conditioned for operation.

12. In refrigerating apparatus, the combination of means defining firstand second chambers, an evaporator structure having first and aisaososecond portions disposed for cooling the air in the first and secondchambers, respectively, means for circulating refrigerant through theevaporator portions, a fan for circulating air within one of thechambers in heat transfer relation with its associated evaporatorportion, means responsive to a predetermined tempera- 'ture of the airin said one chamber for conditioning said circulating means and saidfanfor operation, means responsive to a predetermined temperature of theevaporator portion in the second chamber for conditioning thecirculating means for operation and for rendering the fan incapable ofoperation, and means responsive to the temperature of said firstevaporator portion for controlling the operation of the fan duringperiods when both of said first-mentioned temperature responsive meansare satisfied.

13. In refrigerating apparatus, the combination of meansdefining firstand second cooling chambers, an evaporator associated with each of thechambers, means for circulating refrigerant through the evaporators,means responsive to predetermined high and low temperatures obtainingwithin the first chamber for starting and stopping the refrigerantcirculating means, a fan for translating. air within the second chamberin heat transfer relation with the evaporator therein, means responsiveto predetermined-high and low temperatures obtaining within the secondchamber for respectively initiating and terminating operation of therefrigerant circulating means, and means for effecting operation of thefan at all times excepting periods when said first chamber requirescooling.

14. In a refrigerating system, the combination of means defining achamber 'to be cooled, an evaporator disposed for cooling the air in thechamber, means for circulating refrigerant through the evaporator, a fanfor circulating air within the chamber in heat transfer relation withthe evaporator, means responsive to a predeter mined high temperaturewithin the chamber for initiating operation of the refrigerantcirculating means and'the fan, said temperature responsive means beingeffective to terminate operation of the refrigerant circulating means inresponse to a predetermined low temperature within the chamber, andmeans for terminating operation of the fan in response to apredetermined temperature of the evaporator and after operation of therefrigerant circulating means has been terminated.

LESLIE B. M. BUCHANAN.

